1. Field of the Invention
This invention relates to an optical connector having an optical plug of a structure in which a spring cap is fitted to a plug housing.
2. Description of the Related Art
An optical connector is used in connecting, for example, an optical fiber (or optical fiber cable) which constitutes a multiple transmission circuit in a vehicle such as an automobile to a transmitter, receiver or another cable.
Such an optical connector, as shown in FIG. 9, consists of an optical plug 1 and a not-shown mating receptacle, the optical plug 1 including ferrule units 2, 2, a plug housing 3, and a spring cap 4. The ferrule units 2, 2, each having an optical fiber 5, are assembled to the spring cap 4 and then inserted into the corresponding receiving cavities 6, 6 of the plug housing 3 until the spring cap 4 fits to the plug housing 3.
More specifically, each ferrule unit 2 consists of the optical fiber 5, a spring 7 and a ferrule 8. To the optical fibers 5, 5, the spring cap 4 and the springs 7, 7 are in this order assembled, and then the ferrules 8, 8 so as to be located at the ends of the optical fibers 5, 5. Each spring 7 abuts at one end against the rear end surface of the related ferrule
The plug housing 3, which is of box-like rectangular shape, has the receiving cavities 6, 6 formed to extend longitudinally therethrough. On its upper wall at the center, the plug housing 3 has a locking arm 9 used in coupling with the not-shown receptacle.
The spring cap 4 is designed to fit over the rear end of the plug housing 3 and has at the rear wall a support 10 with throughholes 11, 11 formed therein through which the optical fibers 5, 5 are let out. Each spring 7 abuts at the other (rear) end against the spring cap rear wall at the inner side.
With the spring cap 4 of the above conventional optical connector, however, because as shown in FIG. 10 each optical fiber letting-out throughhole 11 of the support 10 is formed merely cylindrical, if the optical fiber 5 is excessively bent, for example, by accident as shown by the imaginary line, stresses tend to focus on the optical fiber 5 at the throughhole 11, resulting in breakage of the optical fiber 5 and a malfunction in the transmission circuit.
This invention has been accomplished to overcome the above drawback and an object of this invention is to provide an optical connector which protects the optical fiber at its optical-fiber letting-out portion.
In order to attain the object, according to this invention, there is provided an optical connector which comprises: a ferrule unit including an optical fiber, a ferrule rigidly fitted to one end of the optical fiber, and a spring placed around the optical fiber which abuts at one end against the ferrule; a plug housing which receives therein the ferrule unit; and a spring cap having a rear wall and a fiber letting-out portion formed in the rear wall through which the optical fiber is let out, the spring cap being fittable, with the spring abutting at an opposite end thereagainst, to the plug housing, wherein the plug housing has a resilient protecting means which, when the spring cap is fitted to the plug housing, overhangs a part of the optical fiber let out through the fiber letting-out portion of the spring cap.
Preferably, the resilient protecting means comprises a cantilever plate extending in a fitting direction of the spring cap and the plug housing.
Preferably, the resilient protecting means overhangs the part of the optical fiber let out through the fiber letting-out portion, at a side toward which the part of the optical fiber is assumed to be bent.
Preferably, the fiber letting-out portion comprises a slit formed in the rear wall of the spring cap through which the optical fiber and the resilient protecting means extend outside the spring cap.
Advantageously, the spring cap has an optical-fiber support of U-shaped cross section provided on the rear wall of he spring cap to surround, along with the resilient protecting means, the part of the optical fiber let out through the fiber letting-out portion.
Preferably, the spring cap has a plurality of resilient cantilever protecting plates provided on the rear wall of the spring cap to surround, along with the resilient protecting means, the part of the optical fiber let out through the fiber letting-out portion.
Preferably, three of the resilient cantilever protecting plates are provided to be located on left and right sides and a lower side of the fiber letting-out portion to surround, along with the resilient protecting means, the part of the optical fiber on a total of four sides around the part of the optical fiber.